1. Field of the Invention
The present invention relates to a receiving apparatus and a receiving method.
2. Description of the Related Art
When wireless communication is performed, various communication systems are generally used in accordance with a purpose of communication and restrictions of communication environments. The OFDM (Orthogonal Frequency Division Multiplexing) system, for example, is a communication system by which a signal modulated into many carrier waves which are orthogonal to each other and multiplexed is transmitted. One advantage of the OFDM system is being resistant to interference and the OFDM system is used for standard specifications of IEEE802.11a and n and the like. The DSSS (Direct Sequence Spread Spectrum) system is a communication system by which energy of a signal is spread over a wide frequency band for transmission. One advantage of the DSSS system is a speedup of communication by spreading and the DSSS system is used for standard specifications of IEEE802.11b and the like.
Under such circumstances, a plurality of different communication systems may be used in overlapping communication areas or overlapping communication frequencies in a coexisting situation. Thus, in recent years, development of a receiving apparatus having a so-called “double wait” functionality which is capable of receiving two or more radio signals based on different communication systems have been promoted.
With a receiving apparatus for double wait, there arises an issue of erroneous detection that a radio signal according to one communication system is erroneously detected as a signal according to another communication system. Thus, Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2007-523573, for example, proposes a technique to determine whether or not detection is erroneous after a signal received by one communication system being modulated to adaptively adjust a detection process. Japanese Patent Application Laid-Open No. 2006-295464 discloses a technique that supports both the OFDM system and the DSSS system for double wait and changes detection criteria of radio signal in the DSSS system depending on detection conditions of a radio signal in the OFDM system. Japanese Patent Application Laid-Open No. 2006-295465 discloses a technique that determines to which of the communication systems a detected radio signal conforms by comparing output values from two cross-correlators detecting radio signals in the OFDM system and DSSS system.